74vhc74

[Marlowe]

Hello everyone,

I want to build the ASRC like Fedde's Nonoz DAC. But I can not get the IC 74VHC74, could I use 74HC74 instead of 74VHC74?

What is the difference between 74HC74 and 74VHC74?

 

[fedde]

I used the 74ac74 before. I think it's slightly less good, but certainly worth a try!

Fedde

 

[Marlowe]

Thank you Fedde.

I am still confusing the meaning of alphabets between 74 rather.

 

[Elso Kwak]

Hello everyone,

I want to build the ASRC like Fedde's Nonoz DAC. But I can not get the IC 74VHC74, could I use 74HC74 instead of 74VHC74?

What is the difference between 74HC74 and 74VHC74?

Hi marlowe,
Just have a look here:
http://www.diyaudio.com/forums/showthread.php?postid=151664#post151664
I tried AC, HC and VHC. The latter gave the best sound.

😎

 

[PRBS]

This should help you. The article do not mention VHC type. I think VHC means "Very High Speed CMOS"

http://www.xs4all.nl/~ganswijk/chipdir/ttl.htm

 

[Marlowe]

Thanks Elso and PRBS.

And then, how the clock frequency is recommended?

 

[peranders]

Faster is not necessarily better. They may produce more RFI (or they do!) and that can be harmful... Faster logic demands better pcb's (homebrewed may not be good enough), even multi-layer and advanced decuopling.

 

[Guido Tent]

Faster is not necessarily better. They may produce more RFI (or they do!) and that can be harmful... Faster logic demands better pcb's (homebrewed may not be good enough), even multi-layer and advanced decuopling.

and even then I'd stay away from logic that is faster than required as the internal groundbounce cannot be reduced by external layout.

regards

 

[chijen]

Faster is not necessarily better. They may produce more RFI

You are right!

(or they do!) and that can be harmful... Faster logic demands better pcb's (homebrewed may not be good enough), even multi-layer and advanced decuopling.

 

[Marlowe]

I've built the ASRC circuit using KWAK-CLOCK 7 with 48MHz crystal and three Philips 74HC74 chips reclock the three pins from CS8412 to TDA1543 in I2S mode, but it can not work.
There is no sound I heard. 🙁
The output DC of ASRC are 0V (SDATA) and 4.97V(WS & BCK).

I have tried to connect CS8412 to TDA1543 directly (bypass ASRC), and then the DAC is ok.
So the focus of problem is on the ASRC circuit I think.

I measured the pins of 74HC74s, the DC of VCC, PR, and CL all are 4.98V, GND is 0V. Q1 of SDATA is 0 and of WS and BCK both are about 4.97V. D2 and Q2 all are same as Q1.

How can I to do something to test and debug? 😡

thanks!

 

[fedde]

Well, it looks like your clock doesn't work. The DC level of the clock should be around 2.5V ! The DC levels of the I2S on the input should be comparable to the levels on the output. Also, ensure correct voltage on the set and clear pins if present...

Fedde

 

[Marlowe]

Hello Fedde,

The manual of Kwak-Clock 7 is written: "The KWAK-CLOCK will work with any crystal in the range 8 to 24.576 MHz.".
The crystal is 48MHz more than 24.576 in this case, whether it is too high to KWAK-CLOCK can not work?

 

[fedde]

That seems a quite plausible reason for failure...

Though Mr. Kwak is more qualified to answer that question !!! 😉

Fedde

 

[Marlowe]

Hello Fedde,

I've got a mail from Mr.Kwak. The Clock can not work with 48Mhz, indeed. 🙁

I'm curious to know how the frequence of crystal in your NONOZ DAC I.

Thank Fedde and Elso.

 

[fedde]

I used 58 and 100 Mhz. But I didn't use Elso's clock circuit, I used the reclocking circuit!

Fedde

 

[tbla]

BINGO

 

[Bricolo]

does someone have a nice tutorial about reclocking?

 

[Marlowe]

Hi Fedde,

I will try it, thank your help.

 

[fedde]

I'd recommend a frequency around 50 MHz instead of 100 MHz unless you make compact PCB's. Hardwiring 100 MHz circuits is not such a good plan after all you see 😉

Also, the supply and shielding of the circuit needs some attention... (if you don't want to pollute the DAC supply!)

Fedde

 

[HeadSh0T]

Marlowe, in case you don't know, the KWAK-CLOCK circuit is not the same thing as the Asynchronous Reclocking circuit.

The schematic of the Asynchronous Reclocker shows a 100Mhz crystal..

Why don't you use the AR circuit instead?